Iron deficiency is the most common nutrient deficiency in the world. The problem is especially common in poor populations, where red meat—the best source of dietary iron—is too expensive to be eaten often. But iron deficiency is even more common among highly trained endurance athletes, and in female runners most of all. Within this group, it is not diet but aerobic exercise itself that appears to be the main culprit. The solution, however, remains dietary.

Does this mean that serious endurance athletes are required to consume large amounts of red meat? One would hope not, considering that diets heavy in red meat (particularly processed red meat) are associated with unfavorable long-term health outcomes. Fortunately, a new study offers evidence that endurance athletes can improve their iron status without eating more red meat.

Scientists have proposed many explanations for the pervasiveness of iron deficiency among endurance athletes. The strongest explanation centers on inflammation. Prolonged and intense aerobic exercise causes muscle damage followed by an inflammatory response that initiates the repair of damaged muscle tissues. Among the many biochemical changes that occur in the inflammatory state is an increased production of a protein called hepcidin, a regulator of iron metabolism.

When hepcidin levels are high, dietary iron absorption in the intestine is impaired. Although research has shown that hepcidin levels are not chronically elevated in endurance athletes, the transient spikes in this protein that follow each workout appear to be sufficient to lower total iron absorption and cause clinical iron deficiency in many athletes.

When you think of iron deficiency in endurance athletes, you probably think of anemia, a condition where the blood lacks enough red blood cells to support normal functioning. Iron deficiency anemia severely degrades aerobic capacity and endurance performance because red blood cells carry oxygen to the working muscles. But iron deficiency may have similar consequences even in the absence of anemia. That’s because iron is not only a critical constituent of red blood cells, but it also plays a more direct role in aerobic metabolism within the mitochondria, the intracellular “factories” where oxygen is used to break down muscle fuels.

In a 2011 study, researchers at Cornell University investigated the link between iron deficiency and performance in rowers. One hundred and sixty-five female collegiate rowers were screened for their iron status. Of these athletes, 16 were identified as anemic and another 30 as iron deficient without anemia. All of the rowers were asked to report their best 2K rowing time in the past three months. On average, the times of the non-anemic iron-deficient rowers were 21 seconds slower than those of their non-deficient peers. While these results do not establish a causal link between iron deficiency and compromised endurance performance, they do establish a strong associative link that very likely indicates a causal connection. If you’ve been feeling a little sluggish lately in your training, the cause may be an iron deficiency with or without anemia.

The other headline from this study of female collegiate rowers is that nearly 28 percent of the subjects were iron deficient, either with or without anemia. The rate of iron deficiency is lower among male endurance athletes. This gender gap reflects a similar gap in the nonathletic population. Women are generally more likely than men to develop iron deficiency because menstrual blood loss increases their iron needs, yet women typically consume less iron than men do. Complicating matters is the fact that female endurance athletes eat less red meat than their sedentary counterparts. One survey found that 40 percent of nationally competitive female runners avoided red meat “for health reasons.”

Minimizing the intake of red meat—specifically processed red meat—is not a bad idea. Research shows that the people who eat the most processed red meat have a significantly lower life expectancy. But studies have also shown that female endurance athletes who don’t eat red meat high lower iron levels. Can endurance athletes avoid the performance-robbing effects of iron deficiency without accepting the health risks of a meat-heavy diet?

Fortunately, the answer appears to be “yes.” Past research has generally shown that supplementation is about as effective as increased red meat consumption in raising iron levels. But even supplementation may not always be necessary. While red meat is the best source of dietary iron, it is not the only source. Researchers at England’s Manchester Metropolitan University recently investigated whether an iron-rich staple of the Ethiopian diet—teff, a whole grain containing 50 percent more iron than whole wheat—could improve the iron status of female endurance athletes. (It’s worth mentioning that Ethiopia is the world’s second-strongest running nation after Kenya.)

Eleven recreational female runners participated in the study. Initial testing determined that they were not consuming iron in adequate amounts. Their average intake was 10.7 mg per day, well below the recommended intake of 15 mg per day for premenopausal women. Four of the women also tested as iron deficient.

The runners were then asked to replace the bread they normally ate with bread made from teff flour. (If you’ve ever dined at an Ethiopian restaurant, you’ve eaten a particular kind of fermented teff bread known as injera.) This one simple substitution elevated the subjects’ average daily iron intake to 18.5 mg. This increase was associated with significantly improved iron supply to body tissues.

Teff is one of many whole grains that are becoming increasingly popular and accessible as endurance athletes and health-conscious eaters branch out from wheat. Give teff a try and you may find yourself performing a little more like an Ethiopian runner!